Plant growth inhibition with 4-hydroxytetrafluoropyridine and derivatives thereof



United States Patent U.S. CI. 71-76 7 Claims ABSTRACT OF THE DISCLOSUREA process for stunting the growth of monocotyledons which comprisesapplying to the monocotyledons an inhibitor which is4-hydroxytetrafluoropyridine, or a salt, ether or ester thereof, inamount sutficient to inhibit the growth of but insuflicient to kill themonocotyledons.

This invention relates to growth inhibition.

Where grass is not grown for fodder or grazing, much unproductive timemay be spent in cutting it. Every lawnowner appreciates this. Frequentmowing is also necessary in, for example, public parks, recreationgrounds, playing fields and along road verges. It will be seen that aprocess for inhibiting the growth of grass, so as to reduce or eveneliminate the need for such mowings, would be of considerable practicalvalue.

According to the present invention we provide a process for stunting thegrowth of monocotyledons which comprises applying to monocotyledons4-hydroxytetrafluoropyridine, or a salt, ether or ester thereof, inamount sufficient to inhibit the growth of but insufficient to kill themonocotyledons.

Besides the inhibition of ornamental grasses, it is a particular featureof the invention to use 4-hydroxytetrafluoropyridine or a salt or esterthereof to stunt the growth of sugar cane since thereby sugar storage inthe cane is increased and a larger quantity of sugar is recovered fromthe crop. According to this invention sugar cane plants are preferablytreated after emergence and before harvesting.

Another feature of the invention is the use of4-hydroxytetrafluoropyridine and salts, ethers and esters thereof tostunt the growth of cereal plants, particularly wheat.

Modification of growth in this way is useful in that shorter plants arebetter able to resist lodging.

The manufacture and properties of 4-hydroxytetrafluoropyridine have beendescribed by Chambers, Hargreaves and Musgrave, Journal of the ChemicalSociety, 1964, at page 5,634. It is phytotoxic both to monocotyledonsand di-cotyledons and if applied in sufiicient quantity it will killmonocotyledons. Preferred rates of application when carrying out thepresent invention are in the range 0.5 to 10 lbs. per acre, depending onthe tolerance to 4-hydroxytetrafluoropyridine of the monocotyledons tobe treated; in certain circumstances however lesser or greaterquantities may be used.

When a salt, ether or ester of 4-hydroxytetrafluoropyridine is to beused, the rate of application will depend upon the particular compoundselected; in general, however, preferred rates of application are in therange 0.5 lb. to lbs. per acre.

. 4-hydroxytetrafluoropyridine and salts, ethers and esters thereof arepreferably applied to monocotyledonous plants in the form ofcompositions containing the active ingredient in admixture with acarrier comprising a solid diluent, or a liquid diluent containing asurface-active agent. The compositions may be applied tomonocotyledonous plants either before or after their emergence from thesoil. The compositions may be in the form of a powder in which a minorproportion of the active ingredient is in admixture with a majorproportion of a solid diluent. Suitable solid diluents include powderedkaolin, fullers earth, gypsum, chalk, Hewitts earth, and china clay. Ingeneral, liquid compositions are preferred, because they can be appliedmore conveniently.

Liquid compositions usually comprise an aqueous solu tion or dispersionof the active ingredient in water con taining a surface-active agent. Indispersions, the active ingredient can be present in the composition assolid particles or as droplets of a solution of the active ingredient ina water-insoluble solvent. Surface-active agents which may be usedinclude condensation products of ethylene oxide with various substances,for example with alkylated phenols, such as octylphenol and nonylphenol;sorbitan monolaurate, oleyl alcohol, cetyl alcohol, and propylene oxidepolymer. Other agents include calcium dodecylbenzenesulphonate, calciumlignosulphonate, and sodium lignosulphonate. One method of making aliquid composition comprises dissolving the active ingredient in anorganic solvent and then agitating the solution with water containing asurface-active agent. A preferred method comprises first dissolving boththe active ingredient and a surface-active agent in a solvent and thenagitating the solution with water.

The amounts of the active ingredient which may be used in thecomposition can vary widely depending upon the ingredient which is to beused and the lant to which the composition is to be applied. In general,however, compositions containing from 0.1% to 2.0% by weight arepreferred although larger or smaller amounts may sometimes be desirable.

The compositions are conveniently supplied to a user in the form of aconcentrate, which is a composition containing a high proportion of theactive ingredient, and which therefore is generally required to bediluted, usually with water, before application. The concentrates cancontain from 10% to of the active ingredient, although from 20% to 70%is preferred.

An especially satisfactory form of concentrate comprises the activeingredient dispersed in a finely divided state in water in the presenceof a surface-active agent and a suspending agent. Suspending agentswhich are preferred are those which impart thixotropic properties to,and increase the viscosity of the concentrate, for example hydratedcolloidal mineral silicates, montmorillonite, beidellite, nontronite,hectorite, saucorite, cellulose derivatives, and polyvinyl alcohol.Bentonite is particularly preferred as a suspending agent.

Another form of concentrate comprises a wettable powder, that is to say,a mixture of an active ingredient which has been finely divided andmixed with a solid surface-active agent either with or without anadditional solid diluent. When agitated with water, the surface-activeagent dissolves and promotes the dispersion of the active ingredient.

4-hydroxytetrafluoropyridine itself is freely soluble in Water and it istherefore generally preferred to apply it as a solution in watercontaining a surface-active agent. It may also be applied in the solidstate, preferably mixed with a solid diluent, for example bentonite orchina clay.

Water-soluble salts of 4-hydroxytetrafluoropyridine may conveniently beused in the form of aqueous solutions which may contain surface-activeagents.

Salts of 4-hydroxytetrafluoropyridine useful in the process of theinvention include salts of alkali metals, alkaline earth metals,transition metals, and salts of the ammonium and substituted ammoniumions. Preferred salts include sodium and potassium salts.

Preferred ethers include alkyl ethers, particularly the given in Table2. The symbol R used in the formulae C to C alkyl ethers. of Table 2below represents the group Preferred esters of4-hydroxytetrafluoropyridine include F F esters derived from carboxylicacids and sulphonic acids.

Examples of particular compounds which may be used N include thefollowing: 4-acetoxytetrafluoropyridine 4-benzoyloxytetrafluoropyridineTABLE 2 4-methanesulphonyloxytetrafiuoropyridine4-hexanesulphonyloxytetrafiuoropyridine 10 Test compound li z firl'it4-benzenesulphonyloxytetrafiuoropyridine4-p-methoxybenzenesulphonyloxytetrafluoropyridine n4-0-nitrobenzenesulphonyloxytetrafluoropyridine Compound i a4-p-chlorobenzenesulphonyloxytetrafiuoropyridine Suuctum lblacm WheatBarley 4-pentafluorobenzenesulphonyloxytetrafluoropyridine ggg 3 Z? 8ROCH 5 l5 0 The following examples illustrate the invention. ggggg 5 1 8%8 1 EXAMPLE 1 R0C0CH 5 5 55 2 Small plants of wheat and barley (typicalreadily culg s z d li i 5 i5 tured monocotyledonous plants) were sprayedwith figggzg s $2 2 4-hydroxytetrafluoropyridine at a rate equivalent to5 lbs. Z Z Z 1 0 of active ingredient per acre. After two weeks thegrowth ggggz-gflgl-gip it 3 of the plants was assessed in comparisonwith untreated ii g ji 5 40 30 controls. Wheat was found to be reducedin size by about ROSO2-COH4'OCH3P 1 20 0 75% in comparison with thecontrols. There had been no internode growth since application of thespray, and EXAMPLE 4 lmle leaf growth' Exlstmg e were a darker greenThis example illustrates the application of the process than normal andShowed only Shght symptoms of Seoretb of the invention to sugar caneplants. Sugar cane plants although the base of the first leaf hadeotlapsedcm. in height were sprayed with aqueous solutions ordispersions of the compounds of Table 3, in a spray EXAMPLE 2 volumecorresponding to 100 gallons per acre. The spray Small sugar cane plantsgrowing in 4-inch pots of John compositions contained 0.05% of a wettingagent com- Innes compost were sprayed with 4-hydroxytetrafiuoroprising acondensate of p-nonylphenol with from seven pyridine at three rates.Samples of the chemical were pre- 3 to eight molecular Proportions ofethylene OXtde- Followpared by grinding with 1 mm. glass beads in avibration g the application of the compounds to the test P mill for 15minutes in the presence of Dispersol T the height of the Plants Was as rd at intervals of (Di er P i a registered t d k) Pl t were time and theincrease in height recorded. Three plants sprayed t 100 ll i h 0,05% Lir NX were used in each treatment and six plants in the untreated(Lissapol is a registered trademark) in the final ol 40 controls. Thevalue given in Table 3 for the increase in tion. Stern and leaf lengthsof experimental plants measheight is the average Value for the three orsix P ured 19 days after treatment are presented in Table 1. 111 Table3, the symbol R 111 the formulae represents Leaf damage was slight,particularly at lower rates. the group N TABLE 1 [Treatmentsz 4-plantmeans; Control: 12-plant1neans] The results are set Out In Table 3.

Mean length of Length of first Length ot'second stem to last unfurledleaf unfurled leaf Increase in plant height (mm.)

ligule of spindle of spindle Test compound after a period of PercentPercent Percent Rate of Rate of treatment Cm. control Cm. control Cm.control applica- Compound tion, 13 22 30 42 10 lb./acre 21.1 65.1 58.567.3 64.0 62.3 5 No. Structure lb./acre days days days days 8 S5. 5 61.0 70. 2 75. 0 t 0 86. 0 142. 0 173. 5 221. 0 4 100 86.9 100 102 8 1 5L792.7 121.6 195.0 2 34. 0 57. 7 82. 6 131. 7 5 24. 3 21. 7 20. 6 21. 7 531. 7 51. 3 59. 3 86. 0 5 66.0 99.3 128.0 167.7

EXAMPLE 5 EXAMPLE 3 This example illustrates the reduction in growthbrought This example illustrates the application of the process about inCOCkSfOOt Plants and Italian Tye-grass Plants of the invention to wheatand barley plants, Young when treated in accordance With the process ofthe inwheat and barley plants were sprayed with compositions ve tiOIL'comprising dilute aqueous dispersions or solutions of the F0111individual COCkSfOOt Plants y glomemta) compounds of Table 2 below. Thecompositions conwere planted in a four-inch flowerpot. When the plantstained 0.05% of a wetting agent comprising a condensate wereestablished, the foliage was cut off to a level of of p-nonylphenol withfrom seven to eight molecular two inches above the soil. Fifteen dayslater, the foliage proportions of ethylene oxide. The spray volume waswas again cut back to the same height. After two furequivalent to 100gallons per acre. Thepercentage reducther days, the plants were sprayedwith 4-hydroxytetration in size of treated plants as compared withuntreated fiuoropyridine as an aqueous solution containing 0.05%

control plants was assessed after 14 days. Results are of a wettingagent comprising a condensate of p-nonyl- TABLE 4 Amount of 4-hydroxy-Total fresh Mean fresh tetrafluoroweight of weight (gm.) pyridineapplied, cut foliage of foliage Plant species lb./acre (gm.) per plantCocksfoot 5 84. 64 21. 16 D 2 84. 13 21. 03 Do l 0 105. 36 26. 34Italian rye-grass. 5 87. 60 43. 8 D0 2 93. 49 46. 75 Do 0 220.19 55.05

1 Control.

It is apparent from the above figures that the higher rate ofapplication of 4-hydroxytetrafluoropyridine caused a reduction ofapproximately 20% in the fresh weight of both grasses.

EXAMPLE 6 4-hydroxytetrafluoropyridine was applied to sugar cane threeweeks before harvest, by spraying it as an aqueous solution containing0.1% w./v. of a surface-active agent comprising a condensate ofp-nonylphenol with from seven to eight molar proportions of ethyleneoxide. Spray rates of from 2.5 to 5 pounds per acre produced a markedincrease in the sugar content of the cane at harvest as compared withuntreated controls.

What is claimed is:

1. A process for stunting the growth of monocotyledonous crop plants,which comprises applying to the plants an inhibitor selected from thegroup consisting of 4-hydroxytetrafluoropyridine, alkali metal, alkalineearth metal, transition metal, ammonium and substituted ammonium saltsof 4-hydroxytetrafluoropyridine, alkyl ethers of4hydroxytetrafluoropyridine, wherein the alkyl contains from 1 to 4carbon atoms, esters of 4-hydroxytetrafluoropyridine derived fromalkanoic and alkanesulphonic acids of 1 to 6 carbon atoms, and esters of4-hydroxytetrafluoropyridine derived from benzoic and benzenesulphonicacids optionally substituted by at least one substituent selected fromthe group consisting of nitro, methoxy, fluorine, and chlorine radicals,said inhibitor being applied in an amount sufficient to inhibit thegrowth of, but insufiicient to kill the plants.

2. A process according to claim 1 in which the monocotyledons aregrasses.

3. A process according to claim 1 in which the mono cotyledons are sugarcane plants.

4 A process according to claim 1 in which the monocotyledons are cerealplants.

5. A process according to claim 1 wherein the inhibitor is applied at arate of from 0.5 to 20 lbs. per acre.

6. A process according to claim 1 wherein the inhibitor is a sodium orpotassium salt of 4-hydroxytetrafluoropyridine.

7. A processing according to claim 1 wherein the inhibitor is acarboxylic or sulphonic acid ester of 4-hydroxytetrafluoropyridine,

References Cited UNITED STATES PATENTS 3,234,228 2/ 1966 Johnston et a17l94 3,249,419 5/ 1966 Martin 7l94 3,256,290 6/1966 Johnston et a1. 7l943,317,542 5/1967 Haszeldine et a1 7l94 3,409,624 11/1968 De Selms 7l94OTHER REFERENCES Vaculik et al.: The Eifect of Several Cmpds, etc.(1966), CA 65, p. 4564 (1966).

Dow: Pohyhalo-A-Pyridinol Plant Growth Regs. (1965), CA 63, pp. 2329-30(1965).

Chambers: 1079, Polyfluoro Hetero Cmpds, etc. Dow: Herbicidalpolyhalopyridines (Neth. Appl. 6,402,443) (1965), CA 64, p. 8152 (1966).

LEWIS GOTTS, Primary Examiner G. HOLLRAH, Assistant Examiner US. Cl.X.-R.

